1. Field of the Invention
The present invention relates to an active matrix type organic light emitting device, and particularly, to an active matrix organic light emitting device and a method for fabricating the same that supplies an electric source to a power supply line for redundancy even if an opening is generated on the power supplying line.
2. Description of the Related Art
Currently, research for electrically conductive organic materials, such as conjugate polymers poly(p-phenylinevinyline) (PPV), for application to light emitting devices is ongoing. In addition, research is being conducted for application of the electrically conductive organic materials to thin film transistors (TFT), sensors, lasers, and photo-electric devices. Presently, light emitting devices made of inorganic phosphor materials are disadvantageous because an operating voltage of the devices should be higher than 200VAC. Accordingly, it is difficult to enlarge an overall size of the devices since they are fabricated using an evaporation process. Thus, achieving a blue light emission is difficult, and the cost for fabricating the devices is high. However, light emitting devices made of organic materials are advantageous because of their superior light emitting efficiency, simplicity in enlarging their overall size, simplified fabricating procedures, and improved blue light emission. In addition, light emitting devices made of organic materials have the ability to be curved. Thus, the light emitting devices made of organic materials are promoted as being the next generation of display devices.
FIG. 1 is a plan view of an active matrix organic light emitting device according to the related art. In FIG. 1, the active matrix organic light emitting device 10 includes a switching TFT 17 and a driving TFT 18. In the active matrix organic light emitting device 10, an Nxc3x97M number of pixels are defined by a plurality of gate lines 11 and a plurality of data lines 13 arranged in a matrix form. Within each of the pixels, the switching TFT 17 is switched as a scanning signal is applied from the gate line 11 and a data signal of the data line 13 is inputted therein, the driving TFT 18 is enabled as the switching TFT 17 is turned ON, and an organic light emitting unit 19 for emitting light is turned ON. In addition, a power line 15 is arranged to be parallel with the data line 13 for applying an excitation signal to the organic light emitting unit 19 when the driving TFT 18 is enabled. A storage capacitor 20 is included to maintain the excited state of the organic light emitting unit 19.
An outer driving circuit (not shown) is disposed along an outer side of the organic light emitting device 10, and is electrically connected to the organic light emitting device 10 through bonding pads 21 and 22 formed on end parts of the gate line 11 and data line 13. The power line 15 is also connected to the outer driving device (i.e., power supplying device). The gate lines 11 and the data lines 13 are directly connected to the outer driving circuit. However, the power line 15 is connected to the outer driving circuit through a power supplying line 23. The power supplying line 23 is formed on a same layer upon which source/drain electrodes of the driving TFT 18 are formed, and is formed of the same metal as the source/drain electrodes. In addition, all of the power lines 15 are electrically connected to the power supply line 23, thereby providing all of the power lines 15 with the exciting signal. When the driving TFT 18 is turned ON by application of a signal transmitted by the switching TFT 17, electric power applied to the power supplying line 23 is applied to the organic light emitting unit 19 through the power line 15, thereby emitting light from the organic light emitting unit 19. Accordingly, an image data is displayed on a screen of the organic light emitting device 10.
In FIG. 1, the power supplying line 23 is formed to extend from the first pixel to the last pixel along a transverse direction, or longitudinal direction of the panel 10. Accordingly, the power supplying line 23 provides respective pixels with the exciting signal. The power supplying line 23 is formed by depositing and etching the same metal material as that of the source/drain electrodes of the driving TFT 18 when the source/drain electrodes are formed. Therefore, the power supplying line 23 may be damaged by inner processing conditions or by outer processing conditions during deposition and/or etching, or by exterior mechanical shock. As a result, an opening is generated in the power supplying line 23, whereby the exciting signal is not transmitted to an adjacent pixel beyond the opening even if the driving TFT 18 is turned ON. Accordingly, the image data is not formed on the adjacent pixel of the organic light emitting device 10, thereby rendering the organic light emitting device 10 operationally inferior.
In FIG. 1, the power supplying line 23 of the organic light emitting device 10 may be divided along a length direction, thereby creating plural power supplying lines. Accordingly, a total number of the power lines 15 connected to the power supplying line 23 is decreased. In addition, the effects of an opening in the power supplying line 23 is reduced. However, when the opening is generated in one power supplying line 23, an entire row of pixels does not operate, thereby forming a strip shape on the screen. Moreover, when the opening is generated between the power supplying line 23 and the data line 13, an entire column of pixels does not operate.
Therefore, an object of the present invention is to provide an active matrix organic light emitting device and a method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an active matrix organic light emitting device having a power supplying line for redundancy on a power supplying line to a supply power to a thin film transistor (TFT) for driving the organic light emitting layer.
Another object of the present invention is to provide a method for fabricating an active matrix organic light emitting device having a power supplying line for redundancy on a power supplying line to a supply power to a thin film transistor (TFT) for driving the organic light emitting layer.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, an active matrix organic light emitting device includes a plurality of gate lines and data lines respectively arranged along transverse and longitudinal directions for defining a plurality of pixel regions, a plurality of power lines arranged substantially parallel to the data lines, at least one switching thin film transistor disposed within one of the pixel regions, at least one driving thin film transistor disposed within the one of the pixel regions, an organic light emitting unit formed within the one of the pixel regions to emit light by application of a signal through one of the power lines as the driving thin film transistor is enabled, and a plurality of power supplying lines having at least two layers electrically interconnected to each other, the power supplying lines electrically connected with the plurality of the power lines to supply the signal to each of the power lines.
In another aspect, an active matrix organic light emitting device includes an array including a plurality of pixel regions defined by a plurality of gate lines and date lines, the array including a plurality of power lines arranged along a direction parallel to the data lines, a driving member disposed within one of the pixel regions, and an organic emitting unit disposed in the one of the pixel regions for emitting light by application of a signal transmitted by one of the power lines according to actuation of the driving member, a power supplying line disposed along a side of the array for applying the signal to the plurality of power lines, and a redundancy power supplying line disposed along the side of the array, wherein the redundancy power supplying line is electrically interconnected to the power supplying line.
In another aspect, an active matrix organic light emitting device includes a substrate having a pixel region and a power driving region, a semiconductor layer on the pixel region, a gate insulating layer disposed along an entire surface of the substrate, a gate electrode and a first power supplying line formed within the pixel region on the gate insulating layer, a first power supplying line formed within the power supplying line region on the gate insulating layer, an intermediate layer disposed over the gate insulating layer, source/drain electrodes disposed within the pixel region on the intermediate layer, a second power supplying line formed within the power supplying line region on the intermediate layer and connected to the first power supplying line, a passivation layer disposed over the pixel region, and an organic light emitting unit within the pixel region on the passivation layer for emitting light by application of a signal through the second power supplying line.
In another aspect, a method for fabricating an active matrix organic light emitting device includes forming a semiconductor layer within a pixel region of a substrate, forming a gate insulating layer over an entire surface of the substrate, forming respectively a gate electrode within the pixel region of the substrate on the gate insulating layer, forming a first power supplying line within a power supplying line region on the gate insulating layer, forming an intermediate layer over the gate insulating layer, forming respectively a source/drain electrode connected to the semiconductor layer within the pixel region, forming a second power supplying line connected to the first power supplying line within the power supplying region on the intermediate layer, forming a passivation layer over the pixel region, and forming an organic light emitting unit on the passivation layer.
In another aspect, a method for fabricating an active matrix organic light emitting device includes forming a semiconductor layer within a pixel region of a substrate, forming a gate insulating layer over an entire surface of the substrate, forming a gate electrode within the pixel region on the gate insulating layer, forming a redundant power supplying line within a power supplying line region on the gate insulating layer, forming an intermediate layer over the gate insulating layer, forming respectively a source/drain electrode electrically connected to the semiconductor layer within the pixel region through the gate insulating layer and intermediate layer, forming a power supplying line within the power supplying region on the intermediate layer, forming a passivation layer over the pixel region, forming an organic light emitting unit on the passivation layer, and electrically interconnecting the power supplying line with the redundant power supplying line by processing side portions of an open circuit portion of the power supplying line with light from a light source when the power supplying line is electrically opened.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.